Welded steel pipe can be divided into straight welded pipe and spiral welded pipe according to the form of the weld. The straight seam welded pipe production process is simple, production, low cost, and rapid development. The strength of spiral welded pipe is generally higher than that of straight welded pipe, and the welded pipe with a larger diameter can be produced with a narrower billet, and the welded pipe with a different diameter can also be produced with the same width billet. But compared with the same length of straight seam pipe, the weld length is increased by 30~ 30, and the production speed is lower.

Common welding problems and solutions of welded steel pipes:

1. Wrong side.

This is a common problem in pre-welding, and the wrong edge is out of tolerance, which directly leads to the degradation or waste of steel pipe. Therefore, the pre-welding needs to strictly control the number of wrong edges.

When the whole steel tube or more than half of the steel tube is out of tolerance, it is usually because:

(1) The opening seam is not adjusted in place;

(2) The sealing press roll is not adjusted in place (the circumferential viewpoint of the press roll is wrong, or the middle line of the tube blank is the axis, the left, and right press roll is not symmetrical, or the radial elongation of the relative press roll is not consistent), there is no pressure circle;

(3) The pre-bending edge is not pre-bending in place, and the plate edge is abundant in the straight edge appearance.

When the head or tail of the tube is out of alignment, it is usually because:

(1) The bearing of the import and export roller table is wrong;

(2) The middle of the ring frame is wrong;

(3) The joint press roller is not well rounded, and the azimuth error of a single press roller;

(4) Forming is not good (after forming the two ends of the tube blank concave and convex difference is larger;

(5) the opening seam width is more than 150mm);

(6) The pressure of the hydraulic system is shaken.

2, the reverse welding tumor, burns through.

The welding tumor on the back, if removed, is time-consuming, and affects the normal production process; Do not eliminate it, affects the internal welding molding and internal welding seam tracking. Burn-through, affect the surface welding and need to repair. The cause of welding tumor and burning through on the opposite side is usually not tight, or the pressure of the hydraulic system is too low; The forming is not good, and the roundness error is large; ③ Improper selection of pre-welding technical parameters. The welding current and arc voltage should be matched with the appropriate welding speed, too much line energy or too low welding speed, easy to produce welding burr and burn through.

3. Stoma.

Pre-welded weld pores cause internal defects in surface welding. The occurrence of pores in pre-welding welds is usually because the maintenance gas is not safe, such as rich in water, pressure flow, etc.; (2) the Welding machine presents some blocking maintenance gas composed of the uneven gas hood, gas stirring; (3) There is corrosion on the groove, oil pollution and so on.

4. Poor weld forming.

Weld forming is poor, affecting the internal welding tracking after the sequence, affecting the stability of the welding process, and then affecting the welding. Weld forming is closely related to the line energy, welding current, arc voltage, welding speed increases, weld penetration, and melting width decreases, resulting in poor weld forming. When there are pores in the weld, a different appearance of weld formation often occurs.

5. Splash.

Pre-welding splashing simple steel pipe appearance or groove, and not easy to remove, and then affect the welding and outer appearance of the steel pipe. The main reason for the spatter is the incorrect composition of the maintenance gas or the incorrect technical parameters. The proportion of argon in the maintenance gas should be determined.

Cangzhou Shenlong Pipe mainly produces seamless steel pipe, straight seam steel pipe, and spiral steel pipe, but also can process galvanized, anti-corrosion coating, has more than 20 years of production history, reliable quality, is a qualified supplier of BP oil, Petro China.